This is post 5 in the series (next: Cooling, previous: Dell Trigger).
When it comes to power supplies for embedded electronics, it's really hard to beat Meanwell. They are easily available, they have a wide selection, and they are reasonably priced. Thus, my search for power supply started with the first Meanwell catalog I found.
After testing the Dell trigger board, my power supply setup crystallized to 48/55V (for my routers), 15/20V for computers, and lastly (optionally) 12V for a modem. Why do I say "optionally"? Well, the option of using a buck regulator for the modem is always open. Since I have my case dimensions predetermined, the choice on whether to use 2 or 3 power supplies will be mostly driven by their dimensions.
As 1U severely restricts the height, my choice fell onto four power supply families:
I wanted to get as small as possible (can I fit 3?), a reasonable amount of power at each voltage (100W+, especially for 15V needed by computers), a reasonably small ripple (less than 200mA, if possible), tight voltage tolerance (1%, ideally), high efficiency (90%+ desired), and lastly robust overload controls (ideally with auto-recovery). Looking at the catalog, I placed the following power supplies on the short list:
| Model | Output | Power | Tol | Ripple | Eff | Dimensions | Input | C Overload | V Overload | PFC | Fan | Cost |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| LRS-35-12 | 12 V 3.0 A | 35 W | ±1% | 120 mV | 86% | 99 x 82 x 30 | 85-264 Vac | Y (auto) | Y (repower) | N | N | $13 |
| LRS-50-12 | 12 V 4.2 A | 50 W | ±1% | 120 mV | 86% | 99 x 82 x 30 | 85-264 Vac | Y (auto) | Y (repower) | N | N | $14 |
| LRS-100-15 | 15 V 7.0 A | 105 W | ±1% | 120 mV | 90% | 129 x 97 x 30 | 85-264 Vac | Y (auto) | Y (repower) | N | N | $17 |
| LRS-100-48 | 48 V 2.3 A | 100 W | ±1% | 200 mV | 91% | 129 x 97 x 30 | 85-264 Vac | Y (auto) | Y (repower) | N | N | $19 |
| LRS-150-24 | 24 V 6.5 A | 150 W | ±1% | 200 mV | 89% | 159 x 97 x 30 | 85-264 Vac | Y (auto) | Y (repower) | N | N | $19 |
| LRS-150-48 | 48 V 3.3 A | 150 W | ±1% | 200 mV | 90% | 159 x 97 x 30 | 85-264 Vac | Y (auto) | Y (repower) | N | N | $25 |
| RS-50-12 | 12 V 4.2 A | 50 W | ±1% | 120 mV | 84% | 99 x 97 x 36 | 88-264 Vac | Y (auto) | Y (auto) | N | N | $19 |
| RSP-150-24 | 24 V 6.3 A | 150 W | ±1% | 150 mV | 89% | 199 x 99 x 30 | 85-264 Vac | Y (auto) | Y (repower) | Y | N | $39 |
| RSP-150-48 | 48 V 3.2 A | 150 W | ±1% | 250 mV | 90% | 199 x 99 x 30 | 85-264 Vac | Y (auto) | Y (repower) | Y | N | $43 |
| RSP-320-48 | 48 V 6.7 A | 320 W | ±1% | 240 mV | 90% | 215 x 115 x 30 | 88-264 Vac | Y (auto) | Y (repower) | Y | Y | $54 |
| UHP-200-12 | 12 V 16.7 A | 200 W | ±1% | 240 mV | 93% | 194 x 55 x 26 | 90-264 Vac | Y (auto) | Y (repower) | Y | N | $58 |
| UHP-200-15 | 15 V 13.4 A | 200 W | ±1% | 240 mV | 94% | 194 x 55 x 26 | 90-264 Vac | Y (auto) | Y (repower) | Y | N | $54 |
| UHP-200-24 | 24 V 8.4 A | 200 W | ±1% | 240 mV | 94% | 194 x 55 x 26 | 90-264 Vac | Y (auto) | Y (repower) | Y | N | $57 |
| UHP-200-48 | 48 V 4.2 A | 200 W | ±1% | 240 mV | 94% | 194 x 55 x 26 | 90-264 Vac | Y (auto) | Y (repower) | Y | N | $59 |
After tinkering with a couple of combinations, including using power supplies from different families, I decided on a homogenous UHP-200-XX setup. They have ridiculously low profile, high power, and high efficiency. On the downside, they do have a bit of a ripple and their cost is quite a hit.
Another setup I could go with would still have UHP-200-15, but combined with LRS-50-12 and LRS-100-48. The downside of this approach would be a bit of a crowded central setup and less robust power supply.
The three power supplies I ended up with are UHP-200-12, UHP-200-15, and UHP-200-55. While the last one might be a surprise since I was leaning more toward 48V, the 55V version has unusually wide adjustment range (45-58V). This means it covers both 48V and 55V thus allowing me some flexibility.
If you look into their datasheet carefully, one will notice that these power supplies require quite a big heatsink. But alas, we cannot solve everything today; there needs to be something for a future me to deal with too. For now, I need to order these three before I change my mind again.